Radius

The radius is one of the two bones in your forearm. It helps you move your arm and wrist. It also supports lots of important tendons, ligaments, muscles and blood vessels.

Your radius, like all bones, can be affected by osteoporosis.

If you break your radius, you might need surgery to repair it and physical therapy to help you regain your strength and ability to move. Because your radius is connected to so many muscles and nerves, injuries to one structure often can affect the others.

What does the radius do?

Your radius has several important jobs, including:

• Helping your forearm and wrist move, flex and rotate
• Holding seven muscles in place
• Stabilizing the rest of your arm, wrist and hand

Where is the radius located?

Your radius is one of the two bones in your forearm, along with your ulna. The radius is on the same side as your thumb. This is also known as the lateral side of your forearm.

The radius rotates over the ulna when you stretch your arm straight out in front of you with your palm facing down. They’re more parallel to each other when you hold your arm straight out with your palm facing up.

The radius is one of the longest bones in your body. Most adults have radius bones that are around 10 inches (25 centimeters) long.

What are the parts of the radius?

Your radius has a small end where it meets your upper arm bone (humerus), a long shaft in the middle that’s slightly curved and a wider end that meets your wrist. Your radius is thicker and slightly shorter than your ulna.

Even though it’s one long bone, your radius is made up of several parts. These include:

• Radial proximal aspect: This is the upper end that connects to your humerus. It contains the radial head, radial neck and radial tuberosity.
• Radial shaft: The shaft is the long middle portion of the radius that supports the weight of your forearm and provides its shape.
• Radial distal aspect: This is the lower end of your radius. It forms the top of your wrist joint. It’s wider than the rest of your radius where it meets your scaphoid and lunate (wrist or carpal bones). The distal aspect includes the styloid process and ulnar notch.

All these parts and labels are usually more for your healthcare provider to use as they describe where you’re having pain or issues. Your provider might use some of these terms to describe where your radius is damaged if you ever break it.

What are the common conditions and disorders that affect the radius?

Some injuries and issues that can affect the radius include:

• Fractures
• Osteoporosis
• Nursemaid elbow
• Dislocated elbow

Signs/symptoms something isn’t working right

Visit a healthcare provider if you know you experienced an injury and you can’t move or use your arm normally. If you think you might have a dislocated elbow, don’t try to fix it yourself. Never let anyone other than a professional healthcare provider try to reset a joint. Keep your arm stable and go to the emergency room.

Visit a healthcare provider if you have symptoms like pain, stiffness or swelling that don’t get better after a few days. Bumps and bruises are normal, but visit a provider if you ever feel enough pain to make you worried.

What’s the difference between the radius and ulna?

Your radius and ulna are the two bones that make up your forearm. They both help your arm and wrist move.

The ulna is slightly longer than the radius. The ulna is on the medial (pinkie) side of the forearm.

The similarities between your radius and ulna might be confusing. So, it’s easier to think of them as equally important pieces of your arm. They work together to support your forearm and wrist. Their shape and how they work together lets your wrist and hand rotate smoothly.